I placed an order on AT&T at 7:00 am EST, and the credit card I used was not linked to my shipping address. AT&T sent me an e-mail as follows:
Unfortunately, we are unable to verify the availability of funds with the card you provided. As a result, your order has not been processed.
Please call us at 1-866-391-0749 by June 22, 2010 to provide updated payment information. Order specialists are available to assist you Monday thru Sunday: 8 a.m. to 12 midnight Eastern Time.
We apologize for the inconvenience and look forward to serving you. If we don't hear from you by June 22, 2010 , with updated payment information, your order will be automatically canceled.
Thank you.
AT&T
I placed 3 more orders on AT&T, all of which hung at the last step (after the payment screen). Apparently they all went through because i got 3 e-mails that all the orders were cancelled because of too many lines blah, blah, blah.
I called AT&T as requested to update my credit card, and after a 45 minute wait, gave the info. The agent told me it went through, and I immediately saw my upgrade eligibility date change online. About a few hours later, I checked the order status, and it did go through and I am all set!
I also reserved one at the Apple Store using the iPhone Apple Store app, just in case.